Custom style with TinyMCE

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1

I tried to define custom styles for TinyMCE as described here: Custom formats example | Docs | TinyMCE

I tried with the following Options value:

{
  tinymce: {
    formats: {
      customformat: {
        inline: 'span',
        styles: {
          color: '#00ff00',
          fontSize: '20px',
        },
        attributes: {
          title: 'My custom format',
        },
        classes: 'example1',
      },
    },
    style_formats: [
      {
        title: 'Custom format',
        format: 'customformat',
      },
    ],
  },
}

But it does not work as desired. Any idea why this does not work?